Simple PIC12F509 code does not work

[ocset]

Hello,
Please do you know why my C code (XC8) for PIC12F509 doesnt work?
All its supposed to do is read a square wave voltage input on GP5, and then change  GP4 from high to low every second low-going of GP5.
However, GP4 is always just staying low. Do you kow why?
 

it builds sucessfully but doesnt work.

Code: [Select]

/*
 * File:   jitter.c
 * Author:
 *
 * Created on 8 sept 2017, 23:55
 */

//this code jitters

//This uses PIC12F509
//MPLAB X IDE
//XC8 C compiler (free)

#define  _XTAL_FREQ 4000000

#include <xc.h>
#include <stdint.h>


//
#pragma config OSC = IntRC      // Oscillator Selection bits (external RC oscillator)
#pragma config WDT = OFF        // Watchdog Timer Enable bit (WDT disabled)
#pragma config CP = OFF         // Code Protection bit (Code protection off)
#pragma config MCLRE = OFF       // GP3/MCLR Pin Function Select bit (GP3/MCLR pin function is MCLR)

//I have not set the MCLR pin as an input because it will be noise susceptible.
//Therefore i set MCLR up as reset, but i will never use it as reset..but will
//simply tie the pin top Vdd on the PCB.

   
//Declare functions which set up the microcontroller
//void    disable_interrupts(void);   //How do this?
//void    disable_pullups(void);      //How do this?

//    TRIS = 0x18;
   
//Declare variables
    uint8_t   count;

void main(void) {
    GP0 = 0;
    GP1 = 0;
    GP2 = 0;
    GP4 = 0;
    GP5 = 0;
    OPTION = 0xD7;
    TRISGPIO = 0x20;
   
    GP4 = 0;
   
    //5 second delay
    for (count=1;count<=50;count++)   {
    __delay_ms(100);
    }


    while(GP5 == 0) ;
    while(GP5 == 1) ;
    //STATUS LOW FIRST
    //When it gets to this point, the STATUS input has just gone low

    __delay_us(500);
    GP4 = 0;              //FET OFF
   
    while(1){
    while(GP5 == 0) ;   //See out the rest of low STATUS
    while(GP5 == 1) ;   //See out the high STATUS
    while(GP5 == 0) ;   //See out the low STATUS
    while(GP5 == 1) ;   //See out the high STATUS 
    //STATUS LOW SECOND
    __delay_us(500);
    GP4 = 1;              //FET ON
    while(GP5 == 0) ;   //See out the rest of low STATUS
    while(GP5 == 1) ;   //See out the high STATUS
    while(GP5 == 0) ;   //See out the low STATUS
    while(GP5 == 1) ;   //See out the high STATUS
    __delay_us(500);
    GP4 = 0;
    }
   
   

    while(1){;}

    return;
}



[Bruce Abbott]

You mean GP4 is staying low?

Seems to work in the simulator, so I suspect a hardware problem. Can you post the schematic and/or a photo of the setup?

[woody]

GP5 is the input, right? So if that stays low, what is it connected to?

Assuming you have real hardware tie an LED (with a series resistor) to GP0 and use that LED as a signal to find out where your program actually comes (I am not familiar with the XC8 compiler so might have the syntax wrong):

gp0=1;
while(1);

This always helps me to find out where my program takes an unexpected left turn.

And I presume you have executed the mandatory 'blink-a-led' exercise with your hardware to make sure the controller actually runs (has power on the right pins, has its oscillator and fuses configured correctly).

Paul

[Bruce Abbott]

I may have missed the obvious...

All its supposed to do is read a square wave voltage input on pin 5,

Pin 5 is GP2, not GP5. Either input the square wave on pin 2 (GP5) or change the code to use GP2 as the input.
 

[ocset]

Sorry i do apologise, GP5 is the input and GP4 is the output. My Bad. I am kicking myself now.
Thanks Ill try the LED thing etc...the code is so simple that i was hoping to just write it once and done.

[rstofer]

the code is so simple that i was hoping to just write it once and done.

That NEVER happens, I don't care how simple the code may be!